1: static char help[] = "Reads a PETSc matrix and vector from a file and reorders it.\n\
  2:   -f0 <input_file> : first file to load (small system)\n\
  3:   -f1 <input_file> : second file to load (larger system)\n\n";

  5: /*
  6:   Include "petscmat.h" so that we can use matrices.
  7:   automatically includes:
  8:      petscsys.h       - base PETSc routines   petscvec.h    - vectors
  9:      petscmat.h    - matrices
 10:      petscis.h     - index sets            petscviewer.h - viewers
 11: */
 12: #include <petscmat.h>

 14: int main(int argc, char **args)
 15: {
 16:   Mat             A;                        /* matrix */
 17:   PetscViewer     fd;                       /* viewer */
 18:   char            file[PETSC_MAX_PATH_LEN]; /* input file name */
 19:   IS              isrow, iscol;             /* row and column permutations */
 20:   MatOrderingType rtype = MATORDERINGRCM;
 21:   PetscBool       flg;

 23:   PetscFunctionBeginUser;
 24:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 25:   /*
 26:      Determine files from which we read the two linear systems
 27:      (matrix and right-hand-side vector).
 28:   */
 29:   PetscCall(PetscOptionsGetString(NULL, NULL, "-f", file, sizeof(file), &flg));
 30:   PetscCheck(flg, PETSC_COMM_WORLD, PETSC_ERR_USER, "Must indicate binary file with the -f option");

 32:   /* -----------------------------------------------------------
 33:                   Beginning of loop
 34:      ----------------------------------------------------------- */
 35:   /*
 36:      Loop through the reordering 2 times.
 37:       - The intention here is to preload and solve a small system;
 38:         then load another (larger) system and solve it as well.
 39:         This process preloads the instructions with the smaller
 40:         system so that more accurate performance monitoring (via
 41:         -log_view) can be done with the larger one (that actually
 42:         is the system of interest).
 43:   */

 45:   /* - - - - - - - - - - - New Stage - - - - - - - - - - - - -
 46:                          Load system i
 47:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 49:   /*
 50:      Open binary file.  Note that we use FILE_MODE_READ to indicate
 51:      reading from this file.
 52:   */
 53:   PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD, file, FILE_MODE_READ, &fd));

 55:   /*
 56:      Load the matrix; then destroy the viewer.
 57:   */
 58:   PetscCall(MatCreate(PETSC_COMM_WORLD, &A));
 59:   PetscCall(MatSetType(A, MATSEQAIJ));
 60:   PetscCall(MatLoad(A, fd));
 61:   PetscCall(PetscViewerDestroy(&fd));

 63:   PetscCall(MatGetOrdering(A, rtype, &isrow, &iscol));
 64:   PetscCall(ISView(isrow, PETSC_VIEWER_STDOUT_WORLD));

 66:   /*
 67:      Free work space.  All PETSc objects should be destroyed when they
 68:      are no longer needed.
 69:   */
 70:   PetscCall(MatDestroy(&A));
 71:   PetscCall(ISDestroy(&isrow));
 72:   PetscCall(ISDestroy(&iscol));

 74:   PetscCall(PetscFinalize());
 75:   return 0;
 76: }

 78: /*TEST

 80:    test:
 81:       requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)
 82:       args: -f ${DATAFILESPATH}/matrices/medium -viewer_binary_skip_info

 84: TEST*/